Seat back rest with an adjustment device for a flexible arching element for adjusting the convex curvature of the back rest

ABSTRACT

A seat back rest with an adjustment device for a flexible arching element (5) arranged on a frame (1) for adjusting the convex curvature of the back rest. According to the seat back rest, it has an additional pelvic support (17) connected to the flexible arching element (5), the pelvic support (17) being composed of an attachment (16, 23, 28) to the flexible arching element (5) directed towards the seat.

BACKGROUND OF THE INVENTION

The invention relates to a seat back rest with an adjustment device fora resilient arching element for adjusting the convex curvature of saidback rest.

FIELD OF THE INVENTION

Such adjustable back rests are widely known, such as from U.S. Pat. No.5,050,930, for example. They are all based on the principle of providingthe back rest with a convex curvature adapted to the person sitting onthe seat so that that person is provided with an ergonomically correctsupport in the area of the spinal column. Various systems are known, bywhich the convex curvature may be adjusted from a shallow to deep curve,however there are also systems in which the position of the peak of thecurve adjusted selectively from shallow to deep may be moved upwards ordownwards along the length of the seat. Back rests with adjustableconvex curvature are also referred to as lumbar supports.

A common feature of these known adjustable back rests is that, inparticular when the convex curvature is adjusted to be severe, a freeunsupported area is left in the pelvic region and this causes the personproblems after long periods in sitting position.

A seat is known from U.S. Pat. No. 4,832,400, which has a back rest witha separately pivoted hip support arranged in the lower area of the backrest. A corresponding hip support is known from U.S. Pat. No. 4,940,284which is fully integrated into the back rest. Adjustment of the backrest is not provided for in these seats.

A seat with a back rest is known from U.S. Pat. No. 4,944,554, which hasa plurality of plates arranged one above the other over the entireheight of the back rest and flexibly connected to one another by meansof bands, said plates being arranged to be individually adjusted, eithermanually or automatically, by means of adjustment devices attached toeach individually, so that the back rest may be given almost any desiredprofile. This back rest is extremely complicated and very expensive tomanufacture as well as requiring a great deal of effort for adjustment.

SUMMARY OF THE INVENTION

The object of the invention is to improve an adjustable seat back restof the aforementioned type in such a way as to ensure that the back, inparticular the pelvis, is also adequately supported directly underneaththe curved area of the back rest, which, according to a further objectof the invention, also has a simple structure and is thereforeinexpensive to manufacture as well as being simple to adjust withoutrequiring special effort for different users.

This object is achieved by a back rest with an adjustment device for aresilient arching element arranged on a frame for adjusting the convexcurvature of said back rest, characterized in that it has an additionalpelvic support connected to said resilient arching element, said pelvicsupport being composed of an attachment to said resilient archingelement directed towards said seat.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in more detail below on the basis of exampleswith reference to the drawings.

FIG. 1 shows a rear view onto a back rest with an arching device and apelvic support secured in the area above the peak of the curve;

FIG. 2 shows a lateral view of the same as FIG. 1;

FIG. 3 shows a back rest with an arching device, the arching element ofwhich has an extension acting as a pelvic support;

FIG. 4 shows a lateral view of the same as FIG. 3;

FIG. 5 shows an arching element with integrated pelvic support made of aplastic plate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A back rest, as shown in FIGS. 1 and 2, is provided with a frame 1 withtwo transverse struts 2 and a guide means 3. The guide means 3 comprisestwo rods 4 arranged parallel to one another. A resilient arching element5 is arranged on the rods 4. The arching element 5 in the embodimentaccording to FIGS. 1 and 2 comprises two resiliently bendable strips 6in parallel arrangement, which are connected to one another by spacedtransverse strips 7. The strips 6, 7 may be made of metal or anymaterial with resilient characteristics--also of a plastic with orwithout reinforcing elements.

The arching element 5 may be provided with a reinforced strip 11 at thelower and/or upper end 8 or 9. The reinforcing strips 11 are preferablyprovided with sleeves 12, which are arranged to slide on the rods 4. Thesleeves 12 are preferably pivoted to the reinforcing plate 10 or thereinforcing strip 11. The embodiment has a tensioning means 13 with ahandwheel 14, forming part of an adjustment device, which is known andtherefore not explained in further detail. In the embodiment with thereinforcing strip 11, a plate 16 acting as a pelvic support 17 issecured at its upper end in the area above the peak 15 of the curve ofthe arching element 5. The plate 16 may also be secured to thelongitudinal and/or transverse strips 6, 7 and its mobility may rangefrom bending resiliently to being almost rigid, and said plate may alsocomprise a lattice, wherein wings, which are each bent forward (notshown), may be provided on both sides to form a bowl-shaped structure intransverse section. The wings provide lateral support for the back.

The plate 16 may be fixedly secured, e.g. by welding, gluing or similarmeans, or may be replaceably and/or adjustably attached, for example bymeans of screws, which are inserted through holes into strips 6 and/or 7and plate 16, in which case these holes may also be in the form ofelongated holes 18, which permit adjustment to various back rest sizesand/or allow the rigidity characteristics of the plate 16 to be changed.

One central spring element 19, or several spring elements 19symmetrically distributed along the lower edge, may be arranged at thefree lower end of the plate 16 to allow for connection to the frame 1,optionally by means of intermediate elements, e.g. transverse struts 2.These spring elements 19 may influence theelasticity/extension--depending on the selected characteristic and thedesired properties--of the plate 16 and thus also of the pelvic support17.

In the embodiment shown in FIGS. 3 and 4, the arching element 5comprises a resilient plate 20 provided with indentations 21 on bothlateral edges parallel to the transverse struts 2, which define lateralwings 22 angled or bent forward for the lateral support. In theembodiment according to FIGS. 1 and 2, plate 20 is also arranged on theupper end so as to slide on the guide means 3. An extension 23 acting aspelvic support 17 is provided at the lower end of the plate 20.According to the embodiment, the plate 20 and the extension 23 are madefrom a single part, which permits particularly simple and thereforeinexpensive manufacture. In the transition area from the plate 20 to theextension 23--preferably at the ends of plate 20--a guide bar 24 ismovably linked to the rear and is pivoted at its other end to the lowertransverse strut 2 of the frame 1. An air cushion (not shown) may beprovided instead of a guide bar 24.

In this embodiment of the back rest, the extension 23 may, however, alsobe manufactured separately from the resilient plate 20, thus allowing awide variety of adjustments to be made to the spring characteristics andto various sizes of back rest, whereas all other parts of the back restare mass produced. The resilient plate 20 may be connected to a separateextension 23 by any known means, for example, by rivet or screw joints,or by any other form of joint, e.g. by plug-in and clamping joints, thusoptionally permitting replacement of the extension 23 for another, whichmay be required in a car seat if there has been a change of carownership. The free end of the extension 23 may in this case also besupported by a spring element (not shown).

FIG. 5 shows a preferred embodiment of an arching element 5 with anintegrated pelvic support 17, which is composed of a single resilientplastic part and may be stamped from a plate or be manufactured bycompression moulding. In this case, the actual arching part is providedwith indentations 21 on both sides which define wings 22. The wings 22may be angled by means of compression moulding by cold or hot pressingin an additional work cycle or at the same time in a manufacturingprocess. The central part of the arching element is provided withrecesses 25, through which the arching properties of the arching element5 may be influenced. A central attachment 26 is located at the lower endof the arching element 5, the width of said attachment correspondingapproximately to the width of the arching element 5 between the bases 27of two opposing indentations 21. Projections 28--four in theembodiment--are machined from the attachment 26, e.g. by stamping,cutting or other shaping, and these projections 28 are only connected tothe arching element 5 at their upper edge.

At the lower end the attachment 26 has an enclosed edge 29 which--inembodiment three--is fixedly connected to the arching element 5 by meansof bridge elements 30. Openings 31 are arranged in the edge 29 and inthe upper edge of the arching element 5, in which the rope tackle or thesleeve of a Bowden cable arrangement (not shown) may be suspended foradjusting the convex curvature of the arching element 5. If the distancebetween the two openings 31 is reduced by the Bowden cable arrangement,the arching element 5 arches and the projections 28, which are eachconnected to the arching element 5 at only one edge, protrude with theirfree ends from the plane section of the attachment 26, thus forming thepelvic support 17.

Material reinforcements (not shown) may also be provided to change thecharacteristics of the arching element 5 and/or the parts of theattachment 26.

Each time the convex curvature is adjusted by means of the respectiveadjustment device, the pelvic support connected to the respectivearching element is also automatically brought into the correct position,irrespective of whether the curvature is adjusted to very severe or veryslight convexity. This ensures both a simple structure and optimumsupport--in particular of the pelvis--and not only optimum support ofthe lumbar region by means of the adjustable back rest.

In the embodiment according to FIGS. 3 and 4, a quite simple adjustmentdevice is possible for the arching element 5--plate 20--, sincepractically only the friction at the pivot point must be overcome foradjustment of the arching element 5, and therefore only a very slightapplication of force is required.

The arching element 5, and the pelvic support 17 with it, may beadjusted in height on the rods 4 by means of various known mechanisms.

We claim:
 1. A seat back rest comprising:a resilient arching elementadapted to be supported at an upper end and a lower end, said resilientarching element arranged on a frame; an adjustment device for adjustinga convex curvature of said resilient arching element; and a plateproviding a pelvic support, said plate being connected at an upperportion thereof to a convex surface of said resilient arching element inan area above a peak of said convex surface of said resilient archingelement, a lower portion of said plate extending below said peak suchthat said plate overlaps said resilient arching element.
 2. The backrest according to claim 1, characterized in that the pelvic support isprovided with reinforcing elements.
 3. A seat back rest comprising:aresilient arching element adapted to be supported at an upper end and alower end, said resilient arching element arranged on a frame; anadjustment device for adjusting a convex curvature of said resilientarching element; and a pelvic support integrally formed at a lower endof said resilient arching element, said pelvic support including aplurality of projections disposed between bridge connections whichconnect a lowermost portion of said lower end of said resilient archingelement to an intermediate portion of said resilient arching element,said projections extending generally vertically downward from saidintermediate portion of said resilient arching element and having endsthereof being free from connection with said lowermost portion of saidresilient arching element.
 4. The back rest according to claim 3,characterised in that the resilient arching element and the pelvicsupport jointly form a single part.
 5. The back rest according to claim3, characterised in that the pelvic support is secured at the lower endof the resilient arching element.
 6. The back rest according to claim 3,characterised in that the resilient arching element is made of plastic.7. The back rest according to claim 3, characterised in that the archingelement is made from a plate.
 8. A seat back rest comprising:a resilientarching element adapted to be supported at an upper end and a lower end,said resilient arching element arranged on a frame; an adjustment devicefor adjusting a convex curvature of said resilient arching element; anda pelvic support integrally formed at a lower end of said resilientarching element; a guide bar having a first end movably linked to atransition area where said resilient arching element and said pelvicsupport engage one another, said guide bar being pivoted at a second endto said frame; and a spring element attached at a first end thereof tosaid pelvic support and attached to said frame at a second end thereof.9. The back rest according to claim 8, characterized in that said pelvicsupport is made of plastic.
 10. A seat back rest comprising:a resilientarching element adapted to be supported at an upper end and a lower end,said resilient arching element arranged on a frame; an adjustment devicefor adjusting a convex curvature of said resilient arching element; anda plate providing a pelvic support, said plate being connected at anupper portion thereof to a convex surface of said resilient archingelement in an area above a peak of said convex surface of said resilientarching element, a lower portion of said plate extending below saidpeak, characterized in that the pelvic support is provided with a freelower end connected to said frame by at least one spring element. 11.The back rest according to claim 10, characterised in that the pelvicsupport is secured at the lower end of the resilient arching element.